move set to ext namespace

aaccess2/src/PairSetAccess.cpp

aaccess2/src/PairSetAccess.h

aaccess2/src/aaccess.cpp

aarbology2/src/aarbology.cpp

acompare2/src/AutomatonCompare.h

acompare2/src/GrammarCompare.cpp

acompare2/src/GrammarCompare.h

acompare2/src/StringCompare.cpp

acompare2/src/StringCompare.h

agenerate2/src/agenerate.cpp

alib2algo/src/arbology/exact/BoyerMooreHorspool.cpp

alib2algo/src/arbology/exact/BoyerMooreHorspool.h

...gy/exact/DeadZoneUsingBadCharacterShiftAndBorderArray.cpp

...logy/exact/DeadZoneUsingBadCharacterShiftAndBorderArray.h

...src/arbology/exact/ExactNonlinearTreePatternAutomaton.cpp

...o/src/arbology/exact/ExactNonlinearTreePatternAutomaton.h

alib2algo/src/arbology/exact/ExactPatternMatch.cpp

alib2algo/src/arbology/exact/ExactPatternMatch.h

...algo/src/arbology/exact/ExactPatternMatchingAutomaton.cpp

alib2algo/src/arbology/exact/ExactSubtreeMatch.cpp